When an icon is displayed, it changes the value of the $icon variable in the document context

Copy/paste the following code (in a 2.1 syntax document):

{{velocity}}
#set($icon = 'XWiki')
Variable before: $icon
$services.icon.render('world')
Variable after: $icon
{{/velocity}}

You obtain:

Variable before: XWiki
(the icon is displayed here)
Variable after: globe

The reason is that DefaultIconRenderer sets the $icon variable to compute the wiki syntax that should be generated to display an icon:
https://github.com/xwiki/xwiki-platform/blob/xwiki-platform-6.3-rc-1/xwiki-platform-core/xwiki-platform-icon/xwiki-platform-icon-default/src/main/java/org/xwiki/icon/internal/DefaultIconRenderer.java#L126

I believed xwiki.parseContent() was executed in an other context than the document one, but it is not.

3 possible fixes:

• make xwiki.parseContent() executed in its own context (could break backward compatibility)
• create a new API to execute velocity code it a new context (or does it exists already?)
• the hacky way (I don't like it of course), put inside "contentToParse" the following code;

  #set($__oldIconValue__xwiki_private_var = $icon)
  ## render the icon here as before
  #set($icon = $__oldIconValue__xwiki_private_var)